1. Field of the Invention
The invention relates to a spindle motor with a casing part (base plate, flange and the like), preferably for application in hard disk drives, wherein the casing part comprises in the proximity of the motor a flange region which, as a rule, is horizontal, in the center of which a sleeve is disposed for receiving the rotor pivotably supported by means of corresponding bearings. In known manner the sleeve is open on both sides and serves, as already stated, for receiving the pivotably supported rotor, wherein in each instance the stationary part of the bearing configuration, with which the rotor is pivotably supported relative to the casing, is secured on the inside of the receiving sleeve. In the case of rolling bearings these can be, for example, the outer ring(s); in the case of a fluid-lubricated radial bearing, this would analogously be the bearing bushing.
2. Description of the Prior Art
To protect the bearing configuration and in order to prevent the penetration of particle-loaded ambient atmosphere into the hard disk drive, it is known within prior art, as depicted in FIG. 4, to close the lower opening of the receiving sleeve with a cover. This cover is preferably adhered on the lower margin of the receiving sleeve, such that a good sealing of the receiving sleeve against the outside results.
According to prior art for this purpose a cover developed substantially as a disk-form body, if needed with an encircling edge, is set into the correspondingly recessed receiving sleeve, fastened with adhesive agent and sealed. Of disadvantage herein is that the cover must be adhered in a separate operating step with additional installation space needing to be provided in order to be able to accommodate the cover and adhere it. Thereby the effective axial height available for the electric drive is reduced.
In U.S. Pat. No. 5,783,886 is disclosed a casing part of a spindle motor with unilaterally closed receiving sleeve, wherein for the pivot bearing of the rotor a passive magnet bearing configuration is employed, which is not comparable with a rolling bearing employed according to the invention.